Synopsis
Select, time and continue mechanical and pharmacological thromboprophylaxis after lower-limb surgery while actively balancing thrombosis, bleeding, renal and neuraxial-anaesthesia risks.
- Assess VTE and bleeding risk on admission, at consultant review and whenever surgery, mobility, renal function, bleeding or clinical condition changes.
- Combine early mobilisation and hydration with procedure-specific prophylaxis; walking is beneficial but does not substitute for indicated anticoagulant or mechanical prevention.
- NICE first-line elective hip options are LMWH for 10 days then aspirin 75 mg or 150 mg daily for 28 days, LMWH for 28 days with stockings until discharge, or rivaroxaban.
- NICE first-line elective knee options are aspirin 75 mg or 150 mg daily for 14 days, LMWH for 14 days with stockings until discharge, or rivaroxaban.
- For fragility fractures of pelvis, hip or proximal femur, offer prophylaxis for one month when VTE risk outweighs bleeding risk: LMWH 6 to 12 hours after surgery or fondaparinux 6 hours after surgery when bleeding risk is low.
- Consider LMWH or fondaparinux during lower-limb immobilisation when thrombosis risk exceeds bleeding risk, and consider stopping if immobilisation continues beyond 42 days.
- Mechanical devices require correct fit, skin and perfusion checks; avoid anti-embolism stockings in severe peripheral arterial disease or other listed contraindications.
- Coordinate every anticoagulant dose with spinal or epidural insertion and removal, renal function and haemostasis; local neuraxial timing protocols and product information are mandatory.
Key red flags
Sudden breathlessness, chest pain, syncope, shock or an increasing oxygen requirement requires immediate assessment for pulmonary embolism and competing postoperative emergencies.
New unilateral calf or whole-leg swelling, tenderness or venous distension requires a DVT pathway rather than simply extending prophylaxis without diagnosis.
Active major bleeding, expanding wound haematoma, haemodynamic decline or a substantial haemoglobin fall requires urgent review and temporary antithrombotic decisions by the responsible team.
New back pain, weakness, numbness or sphincter dysfunction after neuraxial anaesthesia while anticoagulated raises concern for spinal haematoma and needs emergency anaesthetic and spinal assessment.
A platelet fall with new thrombosis after heparin exposure may represent heparin-induced thrombocytopenia; stop all heparin products and obtain urgent specialist advice.
Failure to prescribe or administer post-discharge prophylaxis for the intended duration creates a preventable gap when thrombotic risk remains elevated.
Investigation priorities
Determine whether and how to combine pharmacological and mechanical prevention for the exact procedure and patient.
Management branches
A patient is admitted for lower-limb surgery, fracture care or immobilisation.
- Assess individual VTE and bleeding risks, renal function, platelets, mobility and existing antithrombotic treatment.
- Identify the exact NICE procedure category and select a supported pharmacological and mechanical strategy.
- Coordinate first and last doses with surgery, haemostasis and neuraxial anaesthesia using the local anticoagulation protocol.
- Document the agent, dose, timing, duration, mechanical-device plan and responsible prescriber.